This invention pertains to a vehicle, specifically to computing and storing its trajectory data and sensor data for a manually-driven vehicle. This invention falls into the Classification Definitions of 701/002 and 701/025.
Wheeled unmanned vehicles are widely adopted in manufacturing, services, and other industries. For instance, in manufacturing factories, they are used for unmanned material handling tasks. In semiconductor clean rooms, unmanned vehicles with articulated manipulators are widely used for silicon cassette handling to eliminate human operators who may produce unwelcome dust. Some hospitals use meal-delivering vehicles for cost-saving measures.
Heretofore, two methods have been known to navigate unmanned vehicles: an electrical/optical method and a programming method. The electrical/optical navigation method uses inductive wires or optical tapes pasted on the floor that are tracked by a vehicle. Another method is navigating a vehicle by computer programming.
U.S. Pat. No. 4,816,998 described a method for a self-pivoting vehicle of computing a steering angle signal by dead reckoning from a predetermined desired trajectory for the vehicle.
U.S. Pat. No. 5,109,340 describes a method for an autonomous vehicle of planning smooth paths by using Clothoid curves that has the feature of curvature continuity.
U.S. Pat. No. 5,170,352 describes a method for an autonomous vehicle of detecting obstacles and detecting the target areas of which the vehicle to be directed. The vehicle is supposed to operate within a predetermined physical area such as on the deck of an aircraft carrier.
U.S. Pat. No. 5,219,036 describes a method for an unmanned industrial trucks of guiding themselves using reference points embedded in the floor and a path-tracking algorithm.
U.S. Pat. No. 5,233,526 describes a method for a driverless vehicle of relocking on a theoretical trajectory during the passage of the vehicle by modifying its curvature. This method guarantees that the curve has the curvature-continuity.
U.S. Pat. No. 5,621,291 describes a method for a self-propelled robotic vacuum cleaner of controlling its motion by ultrasonic sensors.
U.S. Pat. No. 6,134,486 describes a method for a vehicle of tracking a path consisting of directed lines and circles.
U.S. Pat. No. 6,138,064 describes a method for a vehicle of branching from a main line and of merging into the main line again.
These just described navigation methods, however, suffer from a number of disadvantages: (A) As to the electrical/optical method, it is time consuming and costly to implement the wires or optical tapes in the working environment. The cost increases proportionally with its total travelling distance. Furthermore, it is also time consuming and costly to change a once implemented wire/tape because of environmental or mission modifications. In clean room applications, using wires/tapes themselves is not desirable because they may become a source of dust. (B) The programming method has problems also. Measurement of a path in the vehicle's operating environment is needed to program the vehicle. This is a time-consuming task. In some situations, an ideal path for the task cannot be defined easily by programming.
There is another problem where an unmanned vehicle is used for practical applications. A geometrical map of the vehicle environment is necessary for the vehicle's precise motion. Heretofore, there is no economical and simple method known to do this task.